Reverse cycle refrigeration system



Jan. 31, 1967 w. L. MCGRATH 3,300,995

REVERSE CYCLE REFRIGERATION SYSTEM Filed July 26, 1965 INVENTOR.

WILLIAM L. MCGRATH.

ATTORNEY.

United States Patent 3,300,995 REVERSE CYCLE REFRHGERATHON SYSTEMWilliam L. McGrath, Syracuse, N.Y., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Delaware Filed July 26, 1965, Ser. No.474,886 8 Claims. (Cl. 62-416) This invention relates generally to heatpumps of the kind employed for heating and cooling air in an airconditioning plant, more particularly, this invention relates to a novelrefrigeration circuit operable under the reverse cycle principle for usewith heat pumps of the kind described.

It is well known that the coupling of mechanical compressors of arefrigeration system in a series relationship will produce lowerevaporator temperatures or increased capacity at a particular evaporatortemperature. also been proposed to couple mechanical compressors in aseries relationship when a refrigeration system is being used on thereverse cycle for heating in order to produce increased heatingcapacity. However, ince mechanical compressors are costly, any increasedcapacity which is obtainable by their staging is more than off-set bythe high cost involved. It is therefore with the overcoming of theforegoing shortcomings of the prior art while retaining the benefitsthereof that the present invention is concerned.

It is therefore the chief object of the present invention to provide areversible heat pump which will produce staged compression in a simple,eificient and economical manner on both the cooling and heating cycleswithout the use of an additional mechanical compressor.

It is another object of this invention to provide a heat pump whereinthe benefits of staged compression may be obtained by utilizing energyin the cycle which is normally considered as waste energy. In attainingthis object, it is proposed that energy available in the flow ofrefrigerant may be utilized to create pressure differences within thesystem of the kind normally obtained by connecting two mechanicalcompressors in series. With the arrangement of parts contemplated,relatively inexpensive pumping mechanisms such as ejectors' may beemployed in order to create the system flexibility normally achievedwith staged mechanical compressors.

An additional object of the invention is the provision of meansassociated with said ejectors for separating refrigerant flow emanatingfrom the ejectors so that the liquid portion thereof is circulatedthrough the evaporator and the vapor portion thereof is transmitted tothe compressor. Thus, the ejector will create a lower pressure in theevaporator than exists in the suction line receiving refrigerant flowfor passage to the compressor.

The present invention relate to a staged heat pump operable toselectively provide heating or cooling, comprising a compressor, a firstheat exchange coil normally adapted to function as a condenser adaptedto be coupled to the discharge side of said compressor, a second heatexchange coil normally adapted to function as an evaporator adapted tobe coupled to the suction side of said compressor, expansion meanseffectively interposed between said first and second heat exchangecoils, reversing valve means coupled between said coils and saidcompressor for interchanging the functions of said first and secondcoils, and ejector means operatively associated with both said first andsecond coils for producing staged compression on both the heating andcooling cycles.

The present invention will be more fully understood when the followingportions of the specification are read in conjunction with theaccompanying drawing which schematically illustrates a preferredembodiment of the invention.

In the drawing a mechanical compressor 10 is shown It has Patented Jan.31, 1957 having a discharge line 11 and a suction line 12. These linesare connected to a four-way valve 13 which operates in the conventionalmanner. Passageway 14 of valve 13 is adapted to couple discharge line 11to conduit 15 which leads to refrigerant collecting vessel 15' which inturn is coupled by conduit 16 to ejector 17 which is connected tooutdoor coil 16.

When valve 13 is in the position shown in the drawings, therefrigeration system is on the cooling cycle and outdoor coil 16functions as a condenser. The ejector 17 includes a diffusion chamber18, suction chamber 19 and a nozzle Zii. When coil 16 functions as acondenser, refrigerant flows from conduit 15 to collecting vessel 15 andconduit 16' into diffusion chamber 18, then into suction chamber 19 fromwhich it flows to condenser coil 16. It is to be noted that an expansionmember such as capillary 21 is provided between vessel 15 and the end ofcondenser portion 16 which is remote from suction chamber 19 A checkvalve 22 is provided in conduit 23 which has one end connected to nozzle20. As can be seen, thecheck valve 22 and the resistance to flow offeredby capillary 21 causes refrigerant flow to be through condenser portion16, as described above.

Condensed refrigerant therefore fiows from izoil 16 through conduit 24and check valve 25 to the nozzle 26 of e ector 27. The refrigerant thenpasses at high velocity through suction chamber 28 of ejector 27, andthen through diffuser portion 29 Where its pressure is increased abovethe pressure that would normally be present at this point due to thesuction of compressor 10. The refri erant then passes into one end ofconduit 30. The ot her end of conduit 34 is connected to collectingvessel 32' which is in turn connected by conduit 31 to passageway 31 ofreversing valve 13. The indoor heat exchange coil 30 has one end whichcommunicate with suction chamber 28 of e ector 27. The other end of coil30' communicates the collecting vessel 32' through an expansion member32 which may be a capillary, as shown.

The high velocity passage of refrigerant produced by nozzle 26 ofejector 27 causes a lower suction to be created in suction chamber 28.This will cause a portion of the refrigerant in collecting vessel 32' topass through capillary 32 where it is expanded and then through indoorcoil section 30 from which it is induced into suction chamber 28 and isaccelerated by the refrigerant bemg pro ected from nozzle 26. Coilsection 30' thus functions as an evaporator. The mixture of refrigerantbeing pro ected from nozzle 26 With the refrigerant being sucked intosuction chamber 28 from coil section 30' passes into diffuser 29 wherethe pressure of the refrigerant mixture is increased. This mixture thenpasses through conduit 30, and the gaseous portion of the mixture passesthrou h vessel 32, conduit 31', passageway 31 of valve 13 ar id intosuction line 12 of compressor 10. The ejectdr 27 operating in theforegoing manner, produces a compres: sion which causes the suctionpressure of compressor 10 to be increased. This increased suctionpressure in compressor 10 causes a corresponding lower suctiontemperature in indoor coil section 30', thus providing increasedrefrigeration capacity.

The foregoing has described the operation of the re frigeration systemon the cooling cycle. If it is desired to place the refrigeration systemon the heating cycle valve 13 is manipulated so that passageways 14 and31 assume the dotted line positions. As can be seen from the drawing,indoor coil 30' will now function as a condenser and outdoor coil 16 nowfunctions as an evaporator. Under these circumstances, the functions ofejectors 27 and 17 are now reversed so that ejector 27 merely acts as aconduit for refrigerant, while ejector 17 produces compression.

In operation on the heating cycle, refrigerant fiow is from compressorthrough discharge line 11 and conduit 14 (dotted line position) intoconduit 31. The refrigerant flows from conduit 31' into vessel 32', thenthrough conduit 30 into diffuser portion 29 and suction chamber 28, fromwhich it flows into coil section 30'. The one-way valve 25 preventsrefrigerant from passing into conduit 24 and the capillary restrictor 32prevents refrigerant from bypassing coil section 30'. The condensedrefrigerant therefore flows through conduit 23 including check valve 22into the nozzle portion 20 of ejector 17. The high velocity discharge ofrefrigerant from nozzle 20 creates a suction in suction chamber 19 andthus induces refrigerant from collecting vessel 15 through expansionmember 21 and through evaporator 16. The refrigerant coming from coil 16is mixed with the refrigerant projected from nozzle 20 and passed todiffuser 18 where the pressure of the refrigerant is increased. Therefrigerant then passes through conduit 16', vessel 15', and conduit 15to passageway 31 (which is now in the dotted line position), and thenthrough suction line 12 to compressor 10.

As described previously relative to ejector 27, ejector 17 thus producesa stage of compression which in turn increases the suction pressure ofcompressor 10. This increased suction pressure is accompanied by a lowersuction temperature within coil 16 which in turn increases the capacityof the system on the heating cycle.

An indoor coil fan 33 and an outdoor coil fan 34 are provided forpassing air over their respective coils in the direction of the arrows.It can readily be seen that, regardless of whether the outdoor andindoor coils are functioning as condensers or evaporators, the airflowing across these coils is always in a counterflow relationship.

It can thus be seen that I have provided a reversible heat pump which isoperable on both the heating and cooling cycles to produce stagedcompression in a simple, eflicient and economical manner without the useof an additional mechanical compressor.

While I have described a preferred embodiment of my invention, I desireit to be understood that it may be otherwise embodied within the scopeof the following claims.

I claim:

1. A heat pump operable to selectively provide heating or coolingcomprising a compressor, a first heat exchange coil adapted to functionas a condenser normally coupled to the discharge side of saidcompressor, a second heat exchange coil adapted to function as anevaporator normally coupled to the suction side of said compressor,expansion means effectively interposed between said first and secondheat exchange coils, reversing valve means coupled between said coilsand said compressor for interchanging the functions of said first andsecond coils, said expansion means including ejector means and Howrestriction means operatively associated with both said first and secondcoils, said ejector means decreasing the pressure in the coilfunctioning as an evaporator and increasing the pressure of therefrigerant supplied to said compressor.

2. A heat pump as set forth in claim 1 wherein said ejector meanscomprises a first ejector associated with said first coil and a secondejector associated with said second coil, each of said ejectorsdecreasing the pressure in the evaporator and increasing the pressure ofthe refrigerant supplied to said compressor only when the coilassociated therewith functions as an evaporator.

3. A heat pump as set forth in claim 2 wherein each of said ejectorscomprises a nozzle, a suction chamber, and an outlet portion, the nozzleof either ejector, when in operation being coupled with the coilfunctioning as a condenser, said outlet portion being in communicationwith the suction side of said compressor, and said suction chamber beingin communication with the coil functioning as an evaporator.

4. A heat pump as set forth in claim 3 including valve means for causingrefrigerant flow from the outlet portion of either coil functioning as acondenser to the nozzle portion of the ejector associated with the coilfunctioning as an evaporator.

5. A heat pump operable to provide staged compression for either heatingor cooling comprising a compressor, a first heat exchange coil adaptedto be coupled to the discharge side of said compressor for normallyfunctioning as a condenser, a second heat exchange coil adapted to becoupled to the suction side of said compressor for normally functioningas an evaporator, a reversing valve operatively interposed between saidcoils and said compressor for selectively interchanging the functions ofsaid coils, first and second expansion members operatively connected tosaid first and second coils, respectively, for expanding refrigerantwhen its respective coil functions as an evaporator, first and secondejectors operatively associated with said first and second coils,respectively, and valve means interposed between said first and secondcoils for causing the ejector associated with the coil functioning as anevaporator to provide a stage of compression and for causing the otherejector to merely provide a conduit for enabling the flow of refrigerantthrough the coil functioning as a condenser.

6. A method of obtaining staged compression on either the heating orcooling cycle of a refrigeration system operable on the reverse cycleprinciple, said refrigeration system having a compressor, a first heatexchange coil, 21 second heat exchange coil, a first expansion meansassociated with said first heat exchange coil, a second expansion meansassociated with said second heat exchange coil, a reversing valvecoupled between said compressor and said coils, and an ejectorassociated with each of said coils, comprising the steps of compressingthe refrigerant, condensing said refrigerant in one of said coilspassing refrigerant through the expansion means associated with theother of said coils, evaporating refrigerant in the other of said coils,passing refrigerant through the ejector associated with the other ofsaid coils to effect compression of refrigerant and decrease thepressure in the other of said coils, passing said refrigerant to saidcompressor to repeat said foregoing cycle, and selectively manipulatingsaid reversing valve to interchange the functions of said coils andcausing the ejector associated with the coil then functioning as anevaporator to compress refrigerant.

7. A refrigeration system comprising a compressor, a first heat exchangecoil and a second heat exchange coil connected to form a circuit for theflow of refrigerant, expansion means serving each coil and including anejector for transmitting high pressure refrigerant to the coil withwhich it is associated, said ejector serving to induce flow ofrefrigerant through the coils, a refrigerant collection and separationvessel interposed between the ejector and coil for transmitting liquidrefrigerant to the coil and vaporous refrigerant to the compressor.

8. A refrigeration system according to claim 7 wherein said expansionmeans includes a restriction interposed between the vessel and the coilto control flow of liquid refrigerant separated in said vessel.

References Cited by the Examiner UNITED STATES PATENTS 2,044,811 6/1936Randel 62l16 2,513,361 7/1950 Rausch 621l6 3,103,106 9/1963 Tipton 62500X 3,134,241 5/1964 Johnson 62-500 X LLOYD L. KING, Primary Examiner.

6. A METHOD OF OBTAINING STAGED COMPRESSION ON EITHER THE HEATING ORCOOLING CYCLE OF A REFRIGERATION SYSTEM OPERABLE ON THE REVERSE CYCLEPRINCIPLE, SAID REFRIGERATION SYSTEM HAVING A COMPRESSOR, A FIRST HEATEXCHANGE COIL, A SECOND HEAT EXCHANGE COIL, A FIRST EXPANSION MEANSASSOCIATED WITH SAID FIRST HEAT EXCHANGE COIL, A SECOND EXPANSION MEANSASSOCIATED WITH SAID SECOND HEAT EXCHANGE COIL, A REVERSING VALVECOUPLED BETWEEN SAID COMPRESSOR AND SAID COILS, AND AN EJECTORASSOCIATED WITH EACH OF SAID COILS, COMPRISING THE STEPS OF COMPRESSINGTHE REFRIGERANT, CONDENSING SAID REFRIGERANT IS ONE OF SAID COILSPASSING REFRIGERANT THROUGH THE EXPANSION MEANS ASSOCIATED WITH THEOTHER OF SAID COILS, EVAPORATING REFRIGERANT IN THE OTHER OF SAID COILS,PASSING REFRIGERANT THROUGH THE EJECTOR ASSOCIATED WITH THE OTHER OFSAID COILS TO EFFECT COMPRESSION OF REFRIGERANT AND DECREASE THEPRESSURE IN THE OTHER OF SAID COILS, PASSING SAID REFRIGERANT TO SAIDCOMPRESSOR TO REPEAT SAID FOREGOING CYCLE, AND SELECTIVELY MANIPULATINGSAID REVERSING VALVE TO INTERCHANGE THE FUNCTIONS OF SAID COILS ANDCAUSING THE EJECTOR ASSOCIATED WITH THE COIL THEN FUNCTIONING AS ANEVAPORATOR TO COMPRESS REFRIGERANT.